I remember feeling this anxiety. Talking about school and all the types of things that we would all look forward to for a few weeks prior. The best thing I did for them was books. I found several childrens books on the subject. One absolute favorite, was a Pop Up Book, Called Corduroy goes to school.
They are now a second grader, first grader and Kindergarten and they all still want to read it every late August. Hope this was useful.